Brian E. Brzezicki
Copyright 2013
Version 1.00 10/21/2013

Disclaimer
Use this at your OWN risk, do NOT sue me if it breaks your board... if your doing this your board is probably already broken though ;)

Game Board #1 10/21/2013

Problem:

  • Game reboots with RAM 2H error

Troubleshooting/dianosis steps:

  1. Replaced 2114 at 9J/K
  2. Board finished RAM tests then crashes
  3. Pulled all CPUs noticed that Z80A @ 5H/J had broken pins, replaced
  4. Game boots but is missing motion sprites and has other graphic errors
  5. Found custom chip at 5R was missing a pin, soldered on a new pin
  6. motion sprites returned and tiles are fixed though still having some background erors. (background on sprites bad)
  7. Game still being fixed
Game Board #2 10/21/2013

Problem:

  • Game is dead, just flashes of lines and resetting

    • Troubleshooting/dianosis steps:

    1. replaced RAM at 9M
    2. Game boots now, but is missing motion sprites
    3. Noted that 9148s @ 3G and 4J were VERY hot and just happen to be motion sprite RAM!... replaced with new 2148s
    4. Sprites reappeared!
    5. Game works!
    Game Board #3 10/21/2013

    Problem:

  • Game is dead black screen

    • Troubleshooting/dianosis steps:

    1. Noted there is no 18Mhz signal, no H sync or V sync
    2. Replace crystal no change
    3. Replaced 74S04 @ 3B no change
    4. Noted that 3B and 3A had been previously replaced..
    5. Did continuity testing on 3B, found a trace cut where the pad was
    6. Repared trace
    7. Have a 18Mhz signal but no V/H Sync
    8. Replaced custom chip at 4C now get Sync and video
    9. Game now passes RAM test but then fails
    10. EPROM Chip at 2P was put in backwards and broken
    11. Tested each game ROM, found 5 bad, replaced
    12. Game works!
    Game Board #4 10/24/2013

    Problem:

  • Game is dead, game comes up with garbage that just flashes

    • Troubleshooting/dianosis steps:

    1. Replaced TMM2106 / 6116 RAM
    2. Game now reports RAM 0L errors, that is the RAM just replaced, swaping known good RAM still give the same error
    3. Game still being fixed
    Game Board #5 10/25/2013

    Problem:

  • Game is dead, game comes up with garbage that just flashes

    • Troubleshooting/diagnosis steps:

    1. Replaced TMM2106 / 6116 RAM
    2. Game works
    Game Board #6 11/7/2013

    Problem:

  • Game is dead, missing all ROMs

    Troubleshooting/dianosis steps:

    1. Replaced ROMS
    2. Game gave self test errors for 2L, 2H, 3L, 4L
    3. Replaced and socket new 2148s in the positions of the old bad 2114s
    4. game works!
    • Game Board #7 06/18/2014

    Problem:

  • Game is dead, nothing on screen.
  • Owner mentioned game somewhat worked, then they removed chips and did somethign with the power supply then the game stopped working.

    Troubleshooting/dianosis steps:

    1. Pulled all socketed chips as often people who pull them accidentally bend or break them. found a Z80 with pin 20 bent up, pin broke off when trying to bend back, then a few other pins fell off.. replaced. no change
    2. Measured both !HSYNC and !VSYNC test points on the game board... stuck high if I recall.
    3. measured !HSYNC on Sync Generator custom chip @ 5R, was stuck.
    4. measured input !VRSET (pin 16) and !HRESET (pin 13) on 5R, they were stuck low
    5. Swapped the Custom 07xx custom chips at 5R and 1K, measured various outputs on 1K, all dead.
    6. Put back origina chip at 1K, now measured outputs OK, indicated the chip that was at 5R was bad
    7. Put in another replacement 07xx chip at 5R
    8. game works!
    • Game Board #8 09/29/2015

    Problem:

  • Game is missing rows of tiles, some tiles "hi score" are in the wrong place, and well as sprites

    Troubleshooting/diagnosis steps:

    1. looks like rows of tiles/graphics are missing, some text in the wrong places as well as sprites
    2. Fluke RAM test of play field ram (0x8000 - 0x87ff) - getting random BTS errors 0xff on arbitrary addresses.
    3. Found bad 74LS74 @ 4B
    4. Game works!
    • Game Board #9 04/22/2017

    Problem: Game does not work

    Troubleshooting/diagnosis steps:

    1. Found 3 customs and 2 z80s with missing or bent pins, replaced
    2. That cleared up, now getting ram 3H (9h), replaced
    3. Now getting ram 4h (9g/h), replaced
    4. All rams now test OK, but game still resets
    5. Tested all CPUS individually in the main CPU one at a time, one did not work
    6. Replaced, now game boots and passes self test mode
    7. game has video issues (certain tiles) character will not go left There are two burned ROMS, replacing with originals, missing tiles are back
    8. Game works!
    Game Board #10 09/20/2017

    Problem: Game works, but has no sound

    Troubleshooting/diagnosis steps:

    1. Sound is VERY light just can barely hear it
    2. Replaced LM324
    3. Game works!
    4. Repair video at https://www.patreon.com/posts/arcade-pcb-7-dig-14479105
    Game Board #11 03/03/2018

    Problem: Game works, but the digdug character is all shades of blue

    Troubleshooting/diagnosis steps:

    1. Replaced sprite bipolar prom @ 8F
    2. Game works!